Bazel support in what sense? We have basic code nav across every major language, select precise indexers known to work with Bazel (with some degree of work), and we have improved code nav for Bazel files themselves (https://github.com/sourcegraph/sourcegraph/pull/37858), too. Search, of course, works across all languages. Happy to chat more about supporting your specific build environment: https://discord.gg/mBVP4JVBcj
For C++, we do support Bazel via compile_commands.json; we have customers who have used it successfully. Depending on the editor you're using, you probably need to get Bazel to generate a compile_commands.json anyways.
So core code navigation functionality ought to work. There are some issues with different language features (macros, newer C++17 and C++20 features), as well as robustness (crashes on indexing certain code) but we're looking into bringing C++ support up to par with other languages.